Power wrench



Now-25,1941. R. B. wAssoN 2,264,012

' POWER WRENCH Filed March 20, 1940 alumn /1144a? JW/ Patented Nov. 25,1941 UNITED STATES PATE POWER WRENCH Robert B. Wasson, Cranford, N. J.,asslgnor to General Motors Corporation, Detroit, Mich, a

- corporation of Delaware Application March 20, 1940, Serial No. 324,8983 Claims. (CI. 81-54) The invention relates to improvements in poweroperated wrenches, and may in general be considered as an improvement onthat disclosed in Ernest H. Shafi Patent No. 2,119,968 issued June 7,1938. This Shaft patent discloses a wrench embodying a socket at one endwhich is rotated by a power actuated pawl, engageable with a circularseries of ratchet teeth on the socket periphery. Though this wrench hasmet with marked success, it has one definite limitation, namely, that itcan be applied only endwise of a nut, bolt or the like, which is to beturned. In other words, it cannot be moved laterally into engagementwith the member to be turned, in the manner of a so-called open endwrench. Furthermore; merely cutting an entrance opening or throat in theside of the socket, to make it an open end type, will not solve theproblem. for then the series of ratchet teeth would be interrupted bythe entrance opening and the device rendered inoperative as soon as thedriving pawl came into registry with the opening. Accordingly, one aimof the present invention is to provide a power driven wrench having theattributes of ruggedness and simplicity characteristic of the wrench ofthe Shafi patent, but embodying a novel power driving arrangement forrotating a socket having an entrance opening in one side so that it canbe applied to a part, which is to be turned, in the manner of an openend wrench.

Another object is to provide a power wrench having a rotatable socket,with an entrance opening in its side and a peripheral series of ratchetteeth interrupted at the opening, together with a plurality of pawls,power driven in timed relation, and arranged to insure a positive drivefor the socket in all rotary positions of the latter.

Another object is to provide means to split the power impulse drivingthe rotatable socket into vectors of opposite direction so that thepower thrust will be converted to a torque couple;

This is desirable because manufacturers of power wrenches have in thepast, devised wrenches in which the power vector was in one direction.They proved impractical in use because the supporting members with theirnecessarily limited bearing surface rapidly wore under this onedirection load.

The invention also resides in various structural improvements andcombinations of parts by means of which simplicity and low cost ofproduction are combined with effectiveness and versatility of operationand use.

Further objects and advantages-of the invention will become apparent asthe following descriptlon proceeds, taken in connection with theaccompanying drawing in which:

Figure 1 is a general perspective view illustrating the use of a powerwrench embodying the invention; Figure 2 is an enlarged partial planview of the wrench shown in Figure 1; Figure 3 is a longitudinalsectional view substantially along the line 3-3 in Figure 2; Figures 4,5 and 6 are a series of fragmentary stop motion views showing successivepositions of the pawls and ratchet teeth during rotation of the socket;and Figure 7 is a partial longitudinal sectional view similar to Figure3, of a modified form of power wrench embodying the invention.

While the invention is susceptible of various modifications andalternative constructions, I

have shown in the drawing and will herein de scribe in detail thepreferred embodiment, but it is to be understood that. I do nottherebyin-' tend to limit the invention to the specific form disclosed, butintend to cover all-modifications and alternative constructions fallingwithin the spirit and scope of they invention as expressed in theappended claims.

In the first embodiment of the invention selected for illustration(Figure l) the wrench shown includes a cylindrical-socket l0 rotatablyjournaled in the yoke shaped jaw ends of a pair of thin side plates H.,The shank portions of these side plates receive between them a spacerweb or septum I2 projecting from the nose of a cylindrical housing l3,to the outer end of which is screwed the casing l4 of a power unit I5(Figure 3). The unit l5 embodies a suitable power means such as apneumatic motor, power being supplied from this motor, through themedium,

of a novel drive mechanism described more par,- i

ticularly below, for rotating the socket I 0.

It will be observed that the socket ID has a longitudinal entranceopening I6 (Figure 3) in its side. A so-called open end is thus formedfor the wrench through which a device to be turned, such as the couplingI! in Figure 1, may be inserted. vantageous ere the device to be turnedis such that the socket cannot be engaged with it by movementlongitudinally of the member. For example, the coupling I! in Figure 1is threaded at its opposite ends on rods I 8 so that only an open endtype of wrench can be applied to it. The present wrench thus has theversatility peculiar to a. hand operated wrench of the open end type andyet has all of the advantages of a full power operated device. Theinterior of the socket ID has been shown as being of hexagonal This is,of course, particularly adconfiguration and the usual adaptors (notshown) may be inserted in it to'accommodate nuts or the like ofdiilerent diameters or shapes.

To drive the socket III, a pair of motor driven pawls i9 and 20 arearranged to engage a series of ratchet teeth 2| (Figure 3) rigid withthe periphery of the socket. The series of ratchet teeth is c-shaped,rather than annular, because of the interruption in them necessitatedbythe entrance opening IS in the socket. In general, the pawls l9 and 20are reciprocated in opposite vectors to each other and in timed relationby the power unit l5 and are engageable with the ratchet'teeth at pointsspaced apart circumferentially of the socket a greater distance than thewidth of the entrance opening it so that the teeth are engaged by atleast one pawl in all rotational positions of the socket (see Figures 4,5 and 6).

The lower pawl i9 is of the pusher type while the upper pawl 29 is ofthe puller type, being provided with a hook shaped end for engaging theratchet teeth 2|. These pawls are longitudinally reciprocable incorresponding grooves defined between the side plates ii at the lowerand upper edges, respectively, of the central web [2. The pusher pawl I9is yieldably urged upward into engagement with the ratchet teeth by aleaf spring 22 screwed to the housing l3. Similarly, the puller pawl isyieldably urged into engagement with the ratchet teeth by a second leafspring 23 hearing against it and mounted on a U-shaped bracket 24 whichis fixed to and embraces the inner ends of the side plates H (see Figure1).

To connect the pusher pawl l9 in driven relation with the motor in thepower unit i5, an open face barrel cam 25 is provided, which is rigidwith the end of the motor shaft 26, the latter being joumaied insuitable anti-friction bearings 21 in the inner end of the casing i 4(Figure 3). Coacting with this cam 25 is a cam follower roller 28journaled on a pin 29 in the bifurcated inner end of the pusher pawl l9.It will be observed that the inner end of the pin 29 extends laterallyfrom the pawl and has fixed on it a projection 30 receiving the end of ahelical compression spring 3|. The latter is located in a longitudinalbored recess 32 in the housing l3 and yieldably urges the pin 29, to theright (as viewed in Figure 3) to retain the cam follower roller inengagement with the cam. As the motor shaft 29 rotates the pawl I9 ispushed longitudinally outward as the roller 28 rides up on the lobes orhigh points of the cam 25. and the pawl is then reciprocated inward inthe opposite direction by the compression spring 3| as the roller ridesinto the low points on the cam. Since the inner portion of the pawl I9is held loosely in position by the leaf spring 22 its necessary downwardtilting or pivotal motion is permitted so that the pawl nose can passover the ratchet teeth 2| during the return motions of the pawl.

The other, or puller pawl 29 is driven from, and in timed relation with,the pusher pawl l9.

For this purpose a rocker 33 is pivoted in a transverse opening 34 inthe housing web l2 on a transverse'pin 35. Incidentally, this latterpin, as well as a second transverse pin 36 serve-to secure the sideplates II in place. The rounded ends of the rocker 33 are receivedrespectively in slots 31 and 33 in the pawls i9 and 20.

As the pusher pawl I9 is thrust outward by the cam 25 the puller pawl issimultaneously drawn inward by the rocker 33, so that the two pawls actsimultaneously to advance the ratchet 2| a distance of slightly morethan one tooth for each reciprocation of the pawls.

By using pusher and puller pawls, as distinguished from, say, two pusherpawls, it is possible to assure positive actuation of both pawls duringtheir power strokes even though they are driven from an open faced camand are spring returned. Thus the pusher pawl I9 is positively thrustoutward by the cam, during its power stroke, and simultaneously thepuller pawl 29 is positively drawn inward. It is only during theirreturn strokes, when no torque is applied to the ratchet, that thespring 3| moves the pawls.

To prevent inadvertent reverse rotation of the series of ratchet teeth2|, a back-up pawl 39 is utilized. This pawl is block shaped in form andis longitudinally slidable between the side plates II. A pair ofcompression springs 40, located in parallel bores in the outer end ofthe housing web i2, yieldably urge the back-up pawl into engagement withthe ratchet teeth 2|. Two abutments or teeth 4| and 42 are provided onthe back-up pawl. The upper tooth 4| is of rectangular configuration andthe lower tooth 42 triangular so that they will conform to the angularpositions of the ratchet teeth faces presented to them in the mannershown. The pawl teeth 4| and 42 are spaced apart a distance slightlygreater than the width of the entrance opening IS in the socket l0 sothat even when the socket is rotated to present this opening toward theback-up pawl 39', at least one of the latters teeth will always be inengagement with the ratchet teeth. By looking the socket against reverserotation with such a back-up pawl, the device can be used effectually asa hand wrench when the motor is idle.

In the operation of the power wrench described the socket III isinitially located with its entrance opening I6 in registry with thecorresponding openings in the ends of the side plates II (as shown inFigure 3) so that the socket can readily be slipped over a device to beturned, such as the coupling I! (Figure 1). Having engaged the wrenchsocket with the coupling, the operator starts the motor of the powerunit l5 thus starting rotation of the motor outlet shaft 29. Theresultant rotation of the cam 25 reciprocates the pusher pawl I9, asheretofore described, and at the same time the puller pawl 23 isreciprocated in the opposite direction, through the medium of theconnecting rocker 33. In this way a strong torque is applied to thesocket III at generally diametrically opposite points about itsperiphery. Even when the socket entrance opening I3 is in registry withone or the other of the pawls 9 and 20 (Figures 5 and 6) the other pawlis always in engagement with the ratchet teeth so that the drive is notinterrupted nor seriously impaired and a continuous rotation of thesocket is insured.

In Figure 7 a modified form of power wrench has been shown which is ingeneral very similar to that of Figures 1 to 6, inclusive, except that asomewhat different arrangement has been provided for reciprocating thepawls. In the present instance both of them are driven directly from thecam instead of using an intermediate connection from one pawl to thesecond, and in addition, the pawls are positively returned by the camrather than by a spring means. The same reference numerals have beenused for identical parts and, accordingly, their description need notagain be detailed.

In this modified construction, the pawls l9 and 20 correspond to thepawls l9 and 20 in Figure 3 and are similar in construction to themexcept that there is no cross linkage but, instead, each pawl isprovided with a cam follower 28 rotatable on a pin fixed to the innerend of its pawl. These cam follower rollers are received in theperipheral groove of a barrel cam 25. Consequently, as this cam isrotated by the power unit- [5, the pawls l9 and 20 are positivelyadvanced and retracted in timed relation.

The supporting structure is much the same as that previously described,with changes as are necessary to accommodate the differently shaped cam,cam followers, etc. A cylindrical housing l3 is threaded on the end ofthe motor casing M, as before, and the barrel cam 25- is received in theinterior of this housing. A thin shank or projection l2 on the housinghas fixed to its opposite sides the side plates II, by pins 35 and 36,and the socket I0 is rotatably journaled in the yoke shaped ends ofthese side plates. The pusher and puller pawls I9 and 20 are yieldablyretained in position in the grooves defined on the opposite sides of thesupporting structure shank by leaf springs 22* and 23*. In thisinstance, both of these leaf springs are screwed directly to the housingl3 and overlie the respective pawls.

From the foregoing, it will be seen that wrenches embodying the presentinvention afford the extreme flexibility of use andapplicationheretofore peculiar to hand operated open end wrenches, andyet, have all of the advantages of positive power actuation.

I claim:

1. A power wrench of the open end type comprising, in combination, anelongated body struc- V ture having a transversely extending socketrotatablysupported on one end thereof, said socket having 'alongitudinal opening in one side, an

annular series of ratchet teeth on the socketperiphery interrupted atthe side vopening in the socket to leave the same unobstructed,elongated pusher and puller pawls longitudinally reciprocable on saidbody structure and engageable at their outer ends with said ratchetteethat generally diametrically opposite points, a cam follower on theinner end of said pusher pawl, a rotatable cam engageable with saidfollower, a power unit on said body structure for rotating said cam, aspring yieldably urging said pusher pawl longitudinally away from saidteeth and into engagement with the cam, and means including a transverserocker link pivoted intermediate its ends on said body structure andengaged at its opposite ends with said pawls for actuating said pullerpawl in timed relation with the reciprocation of said pusher pawl.

2. A power operated wrench including a power actuated motor, a forwardlyprojecting shank fixed at one end to the motor, a rotatable socketmounted in the opposite end of the shank and provided with an annularseries of ratchet teeth, a pusher rod slidable in a guide slot in oneface of the shank and engageable at one end with said ratchet teeth anddrive connected at its other end with said motor, a puller rod slidablein a guide slot in the opposite face of the shank and engageable at oneend with said ratchet teeth, and a rock lever pivoted within, atransverse slot in the shank and engageable at opposite ends withintermediate portions of the two rods.

3. In a power hand wrench, a power motor having a forwardly projectingshank and an open end socket rotatable in the nose of the shank andprovided with peripheral ratchet teeth, a pair of ratchet tooth engagingrods slidably guided on opposite faces of the shank, and arranged toengage ratchet teeth spaced apart a distance greater than the width ofthe socket opening, drive means between the motor and one of said rodsand a rock lever pivotally mounted in the shank and engaged at oppositeends with said rods for transmitting motion from the motor driven rod tothe other rod.

ROBERT B. WASSON'.

